Answer:
d are small and have isolated themselves.
Step-by-step explanation:
It is a genetic drift pattern.
Founder's effect tends to often occur in populations that are very small and isolated from larger communities.
When a small part of a larger population becomes isolated, the founder's effect can occur.
The implication of this drift is less variation in genetic materials and gene sampling randomly is limited.
This was first outlined by Ernst Mayr in 1942.
An example is the polydactyl syndrome common among the Amish people.